Childhood friends as a romance plot are great, but trying to be first in your craft and your biggest rival are your best friend(s)... that's it

God looking for something/someone in the mortal world; he's willing to forsake his entire existence for her.

Water always is the mystery entity.... for SSL it's time travel and for LotBS is memories. In a sense, they're both time travel and show how love has no time but overall they have the same comedic feeling and "foreigner" trying to get accustomed to life in a new world.